Vibrating screed



Dec. 21, 1965 H. J. MAGINIINISS VIBRATING SCREED 5 Sheets-Sheet 1 FiledMay 9, 1962 INVENTOR.

HAMILTON J. MAGINNISS ATTORNEYS Dec. 21, 1965 H. J. MAGINNISS VIBRATINGSGREED 5 Sheets-Sheet 5 Filed May 9, 1962 INVENTOR.

HAMILTON J. MAGINNISS fiwfifl w ATTORNEYS FIG.6

Dec. 21, 1965 H. J. MAGINQISS 3,224,348

VIBRATING SCREED Filed May 9, 1962 5 Sheets-Sheet 4 42 44 42 J l A 4/ 43I I 72 7 I I 76 FIG.8

INVENTOR. HAMILTON J. MAGINNISS BYWMCDW ATTORNEYS 1965 H. J. MAGININISS3,224,348

VIBRATING SCREED Filed May 9, 1962 5 Sheets-Sheet 5 no I INVENTOR.HAMILTON J. MA GINNISS ATTORNEYS United States Patent 3,2243% VIBRATINGSREED Hamilton J. Maginniss, 563 Russell Road, Mansfield, ()hio FiledMay 9, 1962, Ser. No. 193,468 9 Claims. (Cl. 9448) The present inventionrelates to apparatus for consolidating and finishing concrete. Moreparticularly, the present invention relates to a vibrating screed.Specifically, the present invention relates to a self-propelledvibrating screed having screed boards which can be raised and lowered asthe screed is being propelled.

Screeds are particularly suitable in the construction of roads andhighways, airport runways, floors, bridge decks or any other slab-likeconcrete structure. In the construction of such structures, the concreteis brought to the site and spread on the sub-grade, sub-base orreceiving surface in any of a variety of ways. The concrete must then bestruck to the proper thickness, preferably compacted, and then finishedso that the surface presents the desired texture and smoothness.

Certain prior power operated screeds merely mechanized the manualstrike-off board which rode on the forms and was oscillated back andforth transversely to the direction the screed was traveling. This typescreed presents two major drawbacks: The oscillation of the screed boardimparts severe lateral forces against the side forms; and, unless theconcrete is extremely wet, the screed board will engage and drive theaggregate ahead of the board leaving gouge marks on the surface of theconcrete.

Other prior power operated oscillating screeds are carried on framessupported on side rails, and the oscillation of the screed exertslateral pressures on the side rails.

To obviate these difliculties the vibratory screed was developed. Theprior art vibratory screeds have relatively wide contact area with thecement and vibrate with alow frequency and high amplitude. As a result'the surface of the concrete is patted smooth. This too requires thatthe concrete be extremely wet and results in causing the aggregate towork the surface, both weakening the concrete and causing it to spallwhen subjected to wide temperature variations. Moreover, when suchscreeds ride directly upon the form the vibrations drive the forms intothe ground.

It is therefore an object of the present invention to provide avibrating screed which will strike off and finish low slump concretewhich produces strong slabs.

It is a further object of the present invention to provide a vibratingscreed that will impart deep penetrations of vibrations to the concretein order to thoroughly densify it and yet will not vibrate the forms orseparate the aggregate.

It is a still further object of the present invention to provide aself-propelled vibrating screed in which the screed board can be raisedand lowered while the screed is moving backward and forward.

It is a still further object of the present invention to provide aself-propelled vibrating screed in which the screed boards can be skewedwith respect to the direction the screed is traveling during movement ofthe screed and without manual adjustment.

It is a still further object of the present invention to provide avibrating screed employing tandem screed boards the forward of whichwill serve as a strike-off and consolidating screed and the latter ofwhich serves as a finishing screed.

It is a still further object of the present invention to provide ascreed which is adaptable to finish slabs of various widths, slabs whichincorporate an integral curb therewith and slabs which are to constitutea sub-base for an asphalt surface and which therefore have manholes orscuppers extending above the surface of the slab.

Another object is toprovide a vibrating screed which can be manipulatedby the operator to prevent surging of the concrete behind the screed asit starts to move forwardly.

It is a still further object of the present invention to provide ascreed which is light in weight and which can be readily assembled anddisassembled for ease of transportation.

These and other objects which will become apparent from the followingspecification are accomplished by means hereinafter described andclaimed.

One preferred embodiment of the present invention is shown by way ofexample in the accompanying drawings and described in detail withoutattempting to show all of the various modifications in which theinvention might be embodied; the invention being measured by theappended claims and not by the details of the specification.

In the drawings:

FIG. 1 is a top plan view of a screed according to the presentinvention;

FIG. 2 is an elevation taken substantially on line 2-2 of FIG. 1;

FIG. 3 is an enlarged end elevation taken substantially on line 3-3 ofFIG. 1;

FIG. 4 is an enlarged cross section taken line 4-4 of FIG. 1;

FIG. 5 is a view similar to FIG. 3 showning the articulation of thescreed to raise and lower the screed boards;

FIG. 6 is a top elevation of a screed dolly taken substantially 011 line6-6 of FIG. 4;

FIG. 7 is an enlarged cross section depicting the screed board mountingassembly taken substantially on line 7-7 of FIG. 4;

FIG. 8 is an enlarged cross section of the articulating hinge connectionbetween the tandem members of the screed dolly taken substantially online 88 of FIG. 4;

FIG. 9 is an enlarged cross section depicting the screed board gripplates substantially on line 99 of FIG. 7;

FIG. 10 is a partial frontal elevation of one end of a modified screedboard;

FIG. 11 is a partial frontal elevation of a modified overlapping screedboard; and,

FIG. 12 is a top plan view taken substantially on line 1212 of FIG. 11.

In general a vibrating screed according to the present inventioncomprises two dollies which support at least one screed boardtherebetween. Each of the dollies is comprised of two tandem frameportions. The two portions are joined by a hinge means, and a powermeans articulates the two frame portions about the hinge means. Each ofthe two tandem frame portions is adapted to support a screed board whichis provided with a vibrating means. Mounting means between the screedboard and the respective frame portion is adapted to isolate the framefrom the vibration of the screed board.

Articulation of the tandem frame portions raises and lowers the screedboards but retains at least one wheel on each of the tandem frameportions in contact with the surface on which they roll. By applying acontrolled driving means to at least one of the wheels that retainsrolling contact with the surface on which the dolly travels, andmaintaining an independence between the driving means, the articulatingpower means and the vibrating means for the screed boards, the screedboards can be raised or lowered while the screed is moving forward orbackward and while the vibrators are on or 01?. These controlledmovements at varible speeds substantally on permit tailoring theoperation of the screed to a particular job and offer extremeflexibility of operation for an infinite variety of unique applications.

Referring to the drawings, a screed according to the present invention,indicated generally by the numeral 10, is self-propelled by two spacedapart, identical dollies 11 and 12 which are braced and interconnectedby an adjustably attached transverse bracing beam 13. A catwalk plank14, which is preferably in multiple sections for partial removal, asmore fully hereinafter described, may be removably mounted to theuppermost side of the bracing beam 13 by suitable clip-like fasteningmeans 15 which embrace the sides of the box-like bracing beam 13.

Supported between dollies 11 and 12 are two screed boards, or beams, 16and 17, the front screed board being designated by the numeral 16 andthe rear screed board by the numeral 17. The front screed board 16 isthe strike-01f screed and may be vibrated by two standard, eccentricvibrators 1S and 19 spaced at suitable intervals, although a singlevibrator may be used if desired. The rear screed board 17 is thefinishing screed and is preferably vibrated by a single vibrator 20,similar to vibrators 18 and 19. Both the number of vibrators used oneach board and the number of screed boards vare determined by thetexture desired on the finished surface and the slump characteristic ofthe concrete being screeded and the width of the concrete slab on whichthe machine is operated. It has been found that the preferred embodimentwill screed an extremely low slump concrete to a smooth finish if thevibrators 18, 19 and 20 are of a low amplitude-high frequency variety;i.e., vibrators that have a variable vibrating rate on the order of 3000to 8000 v.p.m.

As best shown in FIG. 3, the dolly 11 of the two identical dollies iscomprised generally of two tandem members 21 and 22 articulately joinedtogether. The member 21 which is generally the forward of the twomembers is constructed in the shape of an inverted V, with two tines 23and 24. The lower end of each tine 23 and 24 is bifurcated to receive awheel 25 mounted on an axle 26 journaled in the bifurcated end of therespective tine. The forward of the two Wheels is designated 25A for apurpose later to become apparent.

Connected to and extending forwardly from each tine 23 and 24 is ascraper 28 which precedes the wheels 25 and 25A to remove any dirt,concrete or other foreign material which may have been inadvertentlydeposited upon the rail 29.

Member 22 which is generally the trailing of the two members isconstructed in the shape of a dog leg with one end 30 pivotally hingedto tine 23 of the V shaped member 20. The other end 31 is bifurcated toreceive a wheel 32 mounted on axle 33 journaled in the bifurcated end 31similarly to axles 26 carrying wheels 25 and 25A. Wheel 23 may also bepreceded by a scraper 34 attached to the inclined portion 35 of dog legmember 22 for cleaning rail 29.

The rail 29 may be a broad or narrow form, an adjacent concrete slab, ora pipe set either on the adjacent finished concrete or in screed chairsmounted on the falsework. For adaptation to this latter type rail thewheels 25, 25A and 32 should be provided with an annular groove 36 inthe peripheral edge thereof.

The end 30 or dog leg member 22 has an angularly inclined face 38 forengaging the rearward face 39 of tine 23 when all three wheels, 25, 25Aand 32 are riding on rail 29. The end 30 is also provided with spacedapart hinge plates 40 and 41 adapted to straddle one or more wing plates42 extending rearwardly from the rearward face 39 of the tine 23. Thehinge plates 40 and 41 and the wing plates 42 have registered bores toreceive a hinge pin 43. If desired, a sleeve 44, also bored to receivepin 43, may be secured between wing plates 42, as best shown in FIG. 8.Articulation of the two members 21 and 22 is accomplished by pivotingthe members on their respective wheels 25A and 32 and about the hingepin 43, as shown in FIG. 5 and described in greater detail hereinafter.

An expansible and contractible power means is connected between themembers 21 and 22 to selectively control the direction and rate ofarticulation. Specifically, a hydraulic cylinder 45 is pivotallyattached to the V shaped member 21, as by a stub shaft 46 extendingoutwardly from the base, or intersection, 48 of tines 23 and 24. Apiston rod 49 provided with a standard piston on one end, not shown, forcontrolled reciprocation within the cylinder 45 is pivotally attached atthe other end to the horizontal portion 50 of the dog leg member 22, asby the stub shaft 51 extending outwardly from portion 50.

The screed boards 16 and 17 are mounted in a suspension system adaptedto isolate the dollies from the vibrations of the screed boards. It hasbeen found that by fabricating the screed boards of laminatedlongitudinal wooden sections, a tougher board results and one with amore uniform density for transmitting the vibrations with more equalfacility along the lengths of the board. Each screed board 16 and 17 isprovided with a channel foot plate 53 suitably secured thereto. The footplate 53 increases the life of the screed board by preventing theabrasion of the concrete from acting directly upon the wooden screedboard. If desired, the channel foot plate 53 may be replaced by a Widechannel up to 12" wide, to plane the concrete surface.

A similar channel cap plate 54 is secured along the top of the screedboard. The cap plate 54 has legs 55 and 56 engaging the sides of thescreed board, as better shown in the FIG. 9 representation of the top ofrear screed board 17.

Each end of the screed boards is gripped for mounting to the respectivedollies 11 and 12 by a pair of opposed grip plates 58 and 59. Each gripplate is preferably a right angular section having a downwardly orientedleg 60 and a horizontally disposed leg 61. Each downwardly oriented leg60 extends along one side of the screed board and is provided with acarrying ledge 62 which extends inwardly in opposed relation to thecarrying ledge on the other grip plate of the pair. The carrying ledges62 form a trackway along which the legs 55 and 56 of top cap plate 54can be selectively slidably engaged.

The upper portion of the downwardly directed legs 60 of each pair ofgrip plates 58 and 59 is bored to receive a tightening means, such asone or more bolts 63, as the horizontally disposed legs 61 arepositioned in sliding juxtaposition. A nut 64 is tightened on each bolt63 to secure the grip plates on to the screed board.

As best shown in FIGS. 3 and 7, the vibration isolating suspensionsystem suspends the screed boards through an upstanding bolt 65 securedto the horizontal leg 61 of grip plate 58 and extending through a slot66 in the horizontal leg 61 of grip plate 59. The dimension andorientation of slot 66 permits the legs 61 of grip plates 58 and 59 toslide without interruption in order to grip and release the screed boardas the nut 64 is tightened or loosened.

Opposed nuts 68 and 69 are threaded on the upstanding portion of bolts65 and are partially tightened against the opposite side of a floatingplate 70 to permit the plate 70 to slide. The bolts 65 extend throughtransverse slots 70A in the floating plates 70, thus allowing the screedboards to skew relative to the forward and rearward travel thereof. Ateach end of the floating plate 70 are one or more downwardly extendingkeepers 71. The keepers 71 engage the inner diameter of a helicalcompression spring 72 at the top thereof. The bottom of each helicalcompression spring 72 rests on a foot plate. As shown in FIG. 3, thefoot plates 73 extend between the face members of tines 23 and 24; thefoot plate 74 is attached to cross the under side of hinge plates 40 and41; and, the foot plate 75 extends downwardly from the horizontalportion 50 of dog leg member 22. Each foot plate 73, 74 and 75 has oneor more upwardly directed keepers 76 for engaging the inner diameter ofeach spring 72 at the bottom thereof.

Thetransverse bracing means 13 which extends between dollies 11 and 12may be attached to each dolly on the upper side of the horizontalportion 50 of dog leg member 22. As shown, a U-shaped retaining plate 78embraces the box beam 13 at each dolly. The legs 79 and 80 of theU-shaped retaining plate 78 are of lesser length than the correspondingsides of the box beam 13 and terminate in outwardly directed flanges 81and 82 which are bored to receive fastening bolts 83. The top plate 84of the horizontal portion 50 of dog leg member 22 has registered boresand may either be tapped or have a nut 85 welded thereto to provide ameans for tightening bolt 83. The beam 13 thus imparts rigid lateralstability to the screed between the dollies 11 and 12 and yet isadjustable to permit adaptation of the screed to various lateraldimensions between the dollies. When the distance between the dollies islessened one or more sections of the catwalk 14 may be removed, asrequired.

An engine-generator unit 86 may also be mounted on the horizontalportion 50 of the dog leg member 22. The engine-generator unit 86 ispreferably demountably attached to the dog leg member to permit easyremoval of the engine-generator unit from the dolly in order to lessenthe weight of the screed in situations where operation of the screedwould be facilitated thereby.

Together with the demountable aspects, the engine-generator unit 86 ispreferably spring mounted to prevent the natural vibrations of theengine from being transmitted to the dolly. The spring suspension of theengine may be comprised to helical springs 88 interpositioned betweenthe engine-generator unit 86 and the horizontal portion 50 of the dogleg member 22 of dolly 11. The springs 88 are maintained in the desiredposition by keepers 89 directed downwardly from the base of theengine-generator 86 and engaging the inner diameter of the top of therespective springs 88, and keepers 90 directed upwardly from thehorizontal portion 50 and engaging the inner diameter of the bottom ofthe respective springs 88.

The electrical current generated by the engine-generator unit 86 is usedto operate the vibrators 18, 19 and 20, the pump motors 89 and'thedriving motors 90.

The pump motors 39, as best shown in FIG. 6, are mounted on the V-shapedmember 21 of each dolly and drive a hydraulic pump 91. The fluid from areservoir, not shown, is pumped through flow control valves 92 intoconduits 93 and then to the cylinder 45 of the expansible andcontractible power means. A control cable 94 leads from the flow valves92 to a remote control station, not shown, where an operator mayselectively control the flow, as hereinafter more fully described.Although a pump 91 is shown on each dolly, if desired, one pump may feedthe cylinders 45 on both dollies.

A driving motor 90 is also mounted on the V-shaped member 21 of eachdolly and is connected through a gear reducer 95 to a driving sprocket96. As best shown in FIG. 4, the driven sprockets 98 are nonrotatablymounted on each axle 26, and are operably interconnected to the drivingsprocket 96 by a chain drive 99 which is also reeved around an idlersprocket 97 to prevent the chain drive from interfering with the screedboard 16. It has been found more desirable to drive both wheels 25 and25A on the V-shaped member 21, although it is well within the scope ofthe present invention to drive only wheel 25A or to drive Wheel 32 orany combination thereof.

The laminated wooden screed boards 16 and 17 may be provided with astraight or cambered bottom edge. Even with a straight bottom edge, someparabolic crown can be imparted to the concrete surface being finishedby the use of wedges or the like inserted at spaced intervals along thescreed board bet-ween the board and the channel 6 foot plates 53. Forproviding a crown on the finished slab, each screed board can also beconstructed of two sections joined in an overlapping arrangement, asshown in FIGS. 11 and 12.

For example, the screed board 16 may be constructed of sections 16A and16B. Section 16B is bored, as at 101, to receive a bolt 102 whichslidably engages a slot 103 in section 16A. A spacer 104, similarlybored, is interposed between section 16A and 16B to allow for thethickness of the adjacent leg portions of the channel foot plates 53Aand 53B. The spacer 104 also assures a solidity of joinder when the nut105 is tightened on to bolt 102.

The section 16B isprovided with a series of bores 106 spaced alongconcentric arcs about the center of bore 101, and section 16A is providewith several bores 107 on each side of the slot 103. Bores 107 aredrilled to align with the bores 106 as the two sections 16A and 16B areinclined at various selected angles with respect to each other and asthe two sections are moved longitudinally of each other at'selectedintervals.

Thus, the nut can be loosened to permit the sections to rotate aboutbolt 102 or to permit section16A to slide longitudinally. When thedesired longitudinal adjustment and inclination of the sections iseifected,bolts 108 are inserted through bores 107 in section 16A and thealigned bores 106 in section 16B. Nuts 109 are tightened on bolts 108and nut 105 is tightened on bolt 102 to lock the sections together.

Moreover, the screed board can be shaped as shown in FIG. 10, to finishan integral curbing 110 with a road surface 11 or an outrigger sectioncan be attached to the end of a screed board.

Further, the pipe rail 29 may be positioned as shown in phantom at 29'and the screed board notched around the rail as indicated at 29A. Thisis possible because there is no lateral movement with the vibratingscreed board. In addition, if the concrete road surface being finishedis to comprise the base for an asphalt road surface and there arescuppers or manholes protruding above the surface, the screed board 16,as shown in FIG. 10, may be provided with flap gates 118 connected tothe board 16 by hinges 119. A latch bolt 120 or other suitable means isused to maintain the gate in closed position until its swingingoperation is desired.

An outrigger section can also be used to undersling the screed boardwhen it is necessary to have the dollies ride above the level of theslab being finished, as, for example, when the rails 29 are placed abovethe curb rebars.

Operation In addition to the remote control of the hydraulic pump motors89, as hereinbefore mentioned, the motors 90 of the driving means forthe wheels 25 and 25A of the two dollies 11 and 12 are also providedwith a remote control. Motors 90 should be of a variety capable ofoperating at variable speeds and also capable of reversal.

Remote control of the vibrators 18, 19 and 20 and the engine-generatorunit 36, as well, affords the most desirable operation of the screed.Independent vertical adjustment of the screeds allows the forward of thetwo screed boards to be operated as a strike-01f and the rearrnost tofunction as a finishing screed.

In FIG. 3, the screed is represented in the down or finishing position.By controlling the frequency of vibration of the screed boards 16 and 17by their respective vibrators 18, 19 and 20, and the rate of forwardtravel of the screed by motors 90, concrete of various consistencies canbe readily finished, and surging of the concrete under the screeds isprevented. As pointed out previously, the number of screed boards usedis also an adjustable variable.

Should it be necessary to refinish a section to correct irregularities,the operator can actuate the cylinder 45 and piston rod 49 of theexpansible and contractible power means, which lies above the hingemeans 43, to articulate the tandem members 21 and 22 so as to raise thescreed boards 16 and 17, as depicted in FIG. 5. At the same time, thedirection the screed is moving can be reversed, via motors 90, and thescreed backed up with reference to the slab being finished.

Then, by controlled operation of the driving motors 90 and theretraction of piston rod 4-9 into cylinder 45, the screed can be movedforwardly coincident with the return articulation of the screed to thefinished position depicted in FIG. 3. The articulation of the dolliesthus occurs on wheels 25A and 32 and about the hinge 43 which liesbetween the wheels (25A and 32) and the cylinder 45. This coordinationof forward movement of the dollies and their articulation preventssurging of the concrete at the point the screed boards contact theconcrete, because the screed can be moved gradually downwardly andforwardly into the concrete so that there is no appreciable build upbehind the screed boards. With the high frequency vibration available itis possible to vibrate the concrete in place both beneath andimmediately in front of the screed boards.

To maintain the screed boards in a substantially vertical disposition,adjustable bumpers 125 may be provided for each screed board. Thebumpers preferably comprise a cylindrical sleeve 126; one end of one isattached to the inclined portion 35 of dog leg member 22 for screedboard 17 and one end of another is attached to the tine 23 of theV-shaped member 21 for screed board 16. The interior of the sleeves 126are threaded to receive a threaded screw post 127 on the outer end ofwhich is a bumper head 128. A lock nut 129 threaded on screw post 127can be tightened against cylinder sleeve 126 to firmly secure theposition of bumper head 128.

The unique suspension and gripping arrangement for attaching the screedboards to the dollies permits the screed to be skewed, as may be desiredwhen finishing super-elevated curves or rhomboid sections. Whenscreeding slabs with widths of from 12 to 32 feet some minor skewing maybe accomplished merely by operating the motor 90 on one dollymomentarily faster than the motor 90 on the other dolly. This moves thefirst mentioned dolly slightly ahead of the other and the slightdifferential of length of screed board required can be accommodated bythe slots 70A in floating plates 70.

At the same time, the tightening bolts 83 holding the retaining plates78 in engagement with beam 13, should be slightly loosened to permit thebeam to similarly accommodate the differential distance between thedollies as the screed is skewed. This latter adjustment together withloosening nuts 64 on bolts 63 also permits the distance between thedollies to be readily adjusted when finishing slabs of different widths.

The adjustment of nuts 68 and 69 on the upstanding bolt 65 is also usedto adjustably raise or lower the screed board with respect to thedollies when they are in the finishing position of FIG. 3, for thepurpose of properly positioning the screed boards relative to theconcrete surface.

It should be apparent that a screed constructed in accordance with theconcepts herein disclosed accomplishes the objects of the invention.

What is claimed is:

1. A screed machine comprising, spaced apart, parallel dollies, tandemscreed boards extending transversely between said dollies, vibratingmeans mounted on each of said screed boards for individually vibratingeach of said screed boards, vibration absorbing supporting meansconnecting said screed boards independently to said dollies, saidsupporting means being adjustable individually to control the verticaldisposition of each of said screed boards with respect to said dollies,said supporting means having a floating means for permitting the limitedlateral movement of said screed boards with respect to at least one ofsaid dollies occasioned when said screed boards are skewed and vibrated,each of said dollies having two tandem frame portions, a hinge meansinterconnecting said tandem frame portions, and power means mounted onsaid dollies for articulating said tandem frame portions about saidhinge means simultaneously to raise and lower said screed boards.

2. A screed machine comprising, spaced apart, substantially paralleldollies, a pair of screed boards extending substantially transverselybetween said dollies, means for pivotally and slidably connecting saidscreed boards to said dollies, means mounted on each of said screedboards to vibrate said screed boards, each of said dollies having twotandem frame portions, each tandem frame portion having wheel means,driving means mounted on said dollies and operatively connected to saidwheel means for selectively and individually propelling said dolliesforwardly or rearwardly, a hinge means interconnecting said tandem frameportions, a power means connected between said tandem frame portions andoperative to articulate said tandem frame portions on said wheel meansand about said hinge means to raise and lower said screed boards.

3. A screed machine comprising, spaced apart, substantially paralleldollies, a pair of screed boards extend ing substantially transverselybetween said dollies, means for pivotally and slidably connecting saidscreed boards to said dollies, means for individually controlling thevertical disposition of each said screed board with respect to saiddollies, means mounted on each of said screed boards to vibrate saidscreed boards, shock absorbing means between said screed boards and saiddollies to isolate the dollies from the vibrations of said screedboards, each of said dollies having two tandem frame portions, eachtandem frame portion having wheel means, driving means mounted on saiddollies and operatively connected to said wheel means for selectivelyand individually propelling said dollies forwardly or rearwardly, ahinge means interconnecting said tandem frame portions, a power meansconnected between said tandem frame portions and operative to articulatesaid tandem frame portions on said wheel means and about said hingemeans simultaneously to raise and lower said screed boards.

4. A screed machine comprising, spaced apart, parallel, dolliessupported on wheel means, each of said dollies having two tandem frameportions, two parallel screed boards extending between said dollies, thecorresponding frame portion on each of said dollies supporting a screedboard therebetween, means mounted on at least one of said screed boardsfor vibrating that screed board, floating means connected between eachof said screed boards and each of said dollies to permit the limitedlateral movement of the screed boards relative to the dollies occasionedby vibration of the screed boards, a hinge means interconnecting saidframe portions above said wheel means, power means connected betweensaid tandem frame portions above said hinge means to articulate saidtandem frame portions on said wheel means and about said hinge means toraise and lower said screed boards simultaneously, and means connectedbetween said screed boards and said dollies to adjust the height of saidscreed boards independently.

5. A screed machine comprising, spaced apart dollies, each of saiddollies having two tandem frame portions, two parallel screed boardsextending between said dollies, the corresponding frame portion on eachof said dollies supporting a screed board therebetween, means mounted onat least one of said screed boards for vibrating that screed board,shock absorbing means between said screed boards and said dollies toisolate the dollies from the vibrations of said screed boards, wheelmeans on the under side of said tandem frame portions, driving meansmounted on said dollies and operatively connected to the wheel means oneach said dolly, floating means connected between each of said screedboards and each of said dollies to permit limited lateral movement ofthe screed boards relative to the dollies occasioned by vibration of thescreed boards, a hinge means interconnecting said frame portions abovesaid wheel means, power means connected between said tandem frameportions above said hinge means to articulate said tandem frame portionson said wheel means and about said hinge means simultaneously to raiseand lower said screed boards.

6. A screed machine comprising, spaced apart dollies, each said dollyhaving two tandem frame portions, one said frame portion being aninverted V-shaped member having two downwardly directed tines, the othersaid frame portion being a dog leg member, hinge means for attaching oneend of said dog leg member to said inverted V-shaped member, wheel meanson the tines of said V-shaped member and on the other end of said dogleg member, two screed boards extending substantially transverselybetween said dollies, two clamping means for each of said screed boardsfor gripping said screed boards at selected positions along the lengththereof, a floating plate pivotally connected to each said clampingmeans and movable with respect thereto along the axis of the screedboard connected thereto, spring means suspending each of said floatingplates from one of said frame members, the two floating plates attachedto the clamping means on each of said screed boards being supported bythe corresponding frame member on the spaced apart dollies, meansmounted on each of said screed boards for individually vibrating saidscreed boards, independent power means connected between said tandemframe portions operative to articulate said tandem members and aboutsaid hinge means to raise and lower said screed boards, and power meansmounted on said dollies for selectively propelling each dollyindependently of the other.

7. A screed machine comprising, spaced apart, parallel, individualdollies, a transverse beam extending between said dollies, connectingmeans for fastening said transverse beam to each of said dollies, saidconnecting means adapted to loosely fasten said transverse beam to saiddollies in a horizontal plane and simultaneously assure lateralstability of said dollies, tandem screed boards extending transverselybetween said dollies, vibrating means mounted on each of said screedboards for individually vibrating each of said screed boards, supportingmeans individually connecting said screed boards to said dollies, saidsupporting means being adjustable individually to control the verticaldisposition of the said screed boards with respect to said dollies,power means mounted on said dollies for selectively propelling eachdolly independently of the other and at selective speeds to permitcontrolled skewing of the screed boards while the machine is inoperation, said supporting means having a resilient floating means topermit limited lateral movement of said screed boards with respect to atleast one of said dollies when said screed boards are vibrated andskewed.

8. A screed machine comprising, spaced apart, parallel, individualdollies, a transverse beam extending between said dollies, connectingmeans for fastening said transverse beam to each of said dollies, saidconnecting means adapted to loosely fasten said transverse beam to saiddollies in a horizontal plane and simultaneously assure the lateralstability of said dollies, tandem screed boards extending transverselybetween said dollies, vibrating means mounted on each of said screedboards for individually vibrating each of said screed boards, supportingmeans connecting said screed boards to said dollies, said supportingmeans being adjustable individually to control the vertical dispositionof said screed boards with respect to said dollies, first power meansmounted on said dollies to raise and lower said screed boards, andsecond power means mounted on said dollies for selectively propellingeach of said dollies independently of the other and at selective speedsto permit controlled skewing of the screed boards while the machine isin operation, and said supporting means having a resilient floatingmeans to permit limited lateral movement of said screed boards withrespect to said dollies when said screed boards are vibrated and skewed.

9. A screed machine comprising, spaced apart, parallel, individualdollies, a transverse beam extending between said dollies, connectingmeans for fastening said transverse beam to each of said dollies, saidconnecting means adapted to loosely fasten said transverse beam to saiddollies in a horizontal plane and simultaneously assure the lateralstability of said dollies, tandem screed boards extending transverselybetween said dollies, vibrating means mounted on each of said screedboards for individually vibrating each of said screed boards, grip meanssecurely holding each of said screed boards in proximity to each of saiddollies, a floating plate attached to each said grip means and movablewith respect thereto along the axis of said screed boards, resilientmeans connecting each floating plate to its respective dolly, means forindividually adjusting the vertical disposition of each of said screedboards with respect to said dollies, and power means mounted on saiddollies for selectively propelling each dolly independently of the otherto permit controlled skewing of the screed boards while the machine isin operation, the movement of each said floating plate along the axis ofthe screed board with which it is associated permitting limited lateralmovement of said screed boards with respect to said dollies when saidscreed boards are vibrated and skewed.

References Cited by the Examiner UNITED STATES PATENTS 413,846 10/1889Chambers 94-45 1,306,353 6/1919 Reynolds 94-45 1,334,483 3/1920 Brookset a1. 94-45 1,479,949 1/ 1924 Ashmore 94-45 1,524,728 2/1925 Busch94-45 2,094,910 10/1937 Baily 94-48 2,110,413 3/1938 Baily 94-482,542,979 2/1951 Barnes 9448 2,584,459 2/1952 Jackson 94-48 2,605,6828/1952 Sarosdy 94-45 2,693,136 11/1954 Barnes 9448 3,008,388 11/1961Nave 94-48 3,015,259 1/1962 Apel et al 94-46 3,110,234 11/1963 Oster94-45 3,118,353 1/1964 Neil 9445 CHARLES E. OCONNELL, Primary Examiner.JACOB L. NACKENOFF, Examiner.

9. A SCREED MACHINE COMPRISING, SPACED APART, PARALLEL, INDIVIDUALDOLLIES, A TRANSVERSE BEAM EXTENDING BETWEEN SAID DOLLIES, CONNECTINGMEANS FOR FASTENING SAID TRANSVERSE BEAM TO EACH OF SAID DOLLIES, SAIDCONNECTING MEANS ADAPTED TO LOOSELY FASTEN SAID TRANSVERSE BEAM TOP SAIDDOLLIES IN A HORIZONTAL PLANE AND SIMULTANEOUSLY ASSURE THE LATERALSTABILITY OF SAID DOLLIES, TANDEM SCREED BOARDS EXTENDING TRANSVERSELYBETWEEN SAID DOLLIES, VIBRATING MEANS MOUNTED ON EACH OF SAID SCREEDBOARDS FOR INDIVIDUALLY VIBRATING EACH OF SAID SCREED BOARDS, GRIP MEANSSECURELY HOLDING EACH OF SAID SCREED BOARDS IN PROXIMITY TO EACH OF SAIDDOLLIES, A FLOATING PLATE ATTACHED TO EACH SAID GRIP MEANS AND MOVABLEWITH RESPECT THERETO ALONG THE AXIS OF SAID SCREED BOARDS, RESILIENTMEANS CONNECTING EACH FLOATING PLATE TO ITS RESPECTIVE DOLLY, MEANS FORINDI-